Field of the Invention
The invention relates to a cabin pressure control, adjustment or regulation system for aircraft, with a controller for a comparison of a command or set point value and an actual value of a cabin pressure, and triggering of an air outlet valve as a function of the comparison.
In such cabin pressure controls, it is usual to control the air inlet valve through a comparison of command or set point and actual values for the pressure prevailing in the cabin and of the cabin pressure expressed as a set point or command value which is dependent on the altitude of the aircraft. The air inlet valve control is typically performed at the rear of the aircraft, in such a way that a predetermined pressure reduction is achieved by means of the cabin air flowing out through the valve.
In earlier conventional cabin pressure control systems, after the comparison of command or set point and actual values was performed, the controller sent a certain signal to the electrical drive for the valve which was connected downstream. Then the valve issued a remote indication, checkback signal or acknowledgement of position, which was compared with the predetermined adjustment value, and readjustment was carried out as needed.
However, that kind of control with continuous remote indication of the valve position entails considerable expense and because of the great number of individual components, it is also more likely to malfunction.